The change in shape and color of keratinic fibers, in particular hair, represents an important sector of modern cosmetics. As a result, the appearance of the hair can be adapted to both current fashion trends and the individual wishes of the individual person. The person skilled in the art knows various dyeing systems for changing hair color, depending on the requirements of the coloring. Oxidation colorants are usually used for permanent, intense colorings with good fastness properties and good gray coverage. Such colorants usually contain oxidation dye precursors, so-called developer components and coupler components, which, under the influence of oxidizing agents, for example, hydrogen peroxide, form the actual dyes with each other. Oxidation colorants are exemplified by excellent, long-lasting coloring results but are also associated with some degree of hair damage.
If the user wants to reduce hair damage or change hair color only temporarily, he can resort to colorants that are based on direct-acting dyes. In this case, already formed dyes diffuse from the colorant into the hair fiber. In comparison with oxidative hair dyeing, the colorings obtained with direct-acting dyes have lower durability and faster leachability. Also, gray coverage, which can be obtained with direct-acting dyes, is usually in need of improvement. Of advantage, however, is the lower hair damage of the coloring with direct-acting dyes.
Depending on the desired color result, the person skilled in the art uses direct-acting dyes of different classes of dyes. The direct-acting dyes known from the prior art include, for example, the class of nitro dyes, the anthraquinone dyes, the azo dyes, the triarylmethane dyes or the methine dyes. All of these classes of dyes should meet a specific requirement profile for use in the cosmetics sector. Thus, direct-acting dyes should provide an intense dyeing result and have the best possible fastness properties. The color result obtained with direct-acting dyes should be influenced as little as possible by to environmental influences, that is, the dyes should have, for example, a good wash fastness, light fastness and friction fastness. Also, chemical influences that the keratinic fibers may be exposed to after the dyeing process (such as perms) should change the color result as little as possible.
Direct-acting dyes can be subdivided into anionic, cationic and non-ionic direct-acting dyes. In cosmetic compositions, these interact in different ways with the other constituents of the compositions. Surface-active active ingredients contained here, such as surfactants or emulsifiers, have a significant influence. These are intended to relieve the keratinic fibers from impurities in the cosmetic compositions and/or to emulsify constituents of the composition itself. However, in this case, depending on the choice of the surface-active substance, it can also lead to interactions between these and the direct-acting dyes, whereby the dyeing result is sometimes significantly deteriorated compared to agents that do not contain surface-active substances.
Surfactants or emulsifiers are amphiphilic (bifunctional) compounds which include at least one hydrophobic and at least one hydrophilic molecular component. The hydrophobic radical is usually a hydrocarbon chain. The hydrophilic radical can have a negative charge, a positive charge, a negative and a positive charge, or no charge, depending on the type of the surfactant.
For anionic surfactants, the hydrophilic component comprises at least one negatively charged hydrophilic head group. Anionic surfactants contain only negative charges.
Cationic surfactants are understood to mean surfactants, that is, surface-active substances, each having one or more positive charges. Cationic surfactants contain only positive charges.
In the hydrophilic molecular component, zwitterionic (amphoteric) surfactants comprise at least one negatively charged and at least one positively charged group. These are spatially separated from each other and lie next to each other, wherein the surfactant is electrically neutral as a whole.
In addition, there are non-ionic (non-ionogenic) surfactants which are exemplified by the absence of electrical charges in the molecules.
It has long been known to the person skilled in the art that many surfactants can significantly degrade the color lift of direct-acting dyes on keratinic fibers. Not all types of surfactants are compatible with all types of direct-acting dyes. The color lift of direct-acting dyes depends to a significant extent on the nature of the surfactants and the nature of the dyes. Anionic surfactants in particular negatively influence the color lift of non-ionic and cationic dyes, but also of anionic dyes. In contrast, cationic surfactants in particular have a negative influence on the color lift of non-ionic and anionic dyes, but also of cationic dyes.
To circumvent these problems, so far, only compositions in which the dye and the surfactant are precisely matched are usually used. It is therefore not possible to use any desired dye with each surfactant or to combine a plurality of dyes with one another in order to achieve the desired shade.
Accordingly, such various compositions are described in the prior art. EP 1 935 455 A1 discloses a composition comprising a direct-acting dye in combination with at least one bioheteropolysaccharide, at least one cationic surfactant and at least one amphoteric surfactant.
WO 2013/041485 A2 describes a composition comprising at least one dye, for example a direct-acting dye, at least one fatty body in the form of a long-chain dialkyl carbonate or dialkenyl carbonate, at least one non-ionic surfactant and at least one cationic and/or amphoteric polymer. Cleaning compositions having different combinations of surfactants are described, for example, in WO 2016/040158 A1, WO 2013/082413 A1 and WO 2014/149019 A1. None of these compositions is especially suitable for the improved color application of direct-acting dyes.
Conventional surfactant-containing colorants having direct-acting dyes (tinting shampoos) are usually optimized either to the best possible dyeing properties or to the best possible cleaning properties or the best possible foam formation. The choice of direct-acting dyes and surfactants that can be combined with each other is limited, so that the flexibility of the possible dye combinations of direct-acting dyes is limited.
The present disclosure therefore had the object of providing a surfactant-containing colorant based on direct-acting dyes, which colorant is compatible with a wide variety of direct-acting dyes and ensures a good color lift.
In addition, the agent should allow a possible large variety of colors, chromaticity and color intensity.
Finally, the agent should also have good cleaning action and good foaming properties and be easily applicable.